IVGCVSW-4210 Create a public API for the common backend files

 * Create a public API for the common backend files
 * Move OutputHandler to armnn internal
 * Remove unused headers

Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>
Signed-off-by: Narumol Prangnawarat <narumol.prangnawarat@arm.com>
Change-Id: I3e86d908b021e3561befa9d45158d87d2cbb18c0
diff --git a/src/backends/backendsCommon/DynamicBackendUtils.cpp b/src/backends/backendsCommon/DynamicBackendUtils.cpp
index b31ce60..ab0006d 100644
--- a/src/backends/backendsCommon/DynamicBackendUtils.cpp
+++ b/src/backends/backendsCommon/DynamicBackendUtils.cpp
@@ -3,7 +3,7 @@
 // SPDX-License-Identifier: MIT
 //
 
-#include "DynamicBackendUtils.hpp"
+#include <backendsCommon/DynamicBackendUtils.hpp>
 
 #include <boost/filesystem.hpp>
 #include <boost/algorithm/string.hpp>